Handover is improved from a 3 G WCDMA UTRAN to a generic access network (GAN) cell. For handover, mobile stations measure signal level from neighbor cells. In a WCDMA UTRAN, measurement of cells having a frequency number different from the serving cell, require the network to generate time gaps so the mobile station can perform measurements on different frequencies. GAN cells do not transmit on their allotted frequency number. This number together with an identifier is used to identify the GAN cell between the MS and RNC. A modified registration procedure permits GAN cells to always have the same frequency number as neighboring UTRAN cells, wherein the MS communicates the current UTRAN cell frequency number to the GAN controller, which adopts this number, and determines the corresponding identifier. The identifier may be the same for all GAN cells, or can be obtained from a mapping table, which maps an identifier to each frequency.